Organic-based optoelectronic components, for example organic light-emitting diodes (OLEDs), are being used increasingly widely in general lighting, for example as a flat light source. An OLED may include an anode and a cathode with an organic functional layer system between them. The organic layers of these flat light sources are in recent methods hermetically shielded by thin-film layers, inter alia against air and moisture, a water permeability of 10−6 g/m2/d or less generally being required for an operating time of about 10 years. At the same time, such a thin-film layer should adhere well on the cathode. The least possible stress differences between the individual layers during and/or after the production process are therefore sought in order to avoid detachment or microcracks in the metallization or thin-film layer, which in turn reduces the storage stability. The stress differences may, for example, occur because of the temperature prevailing and varying during the production process.
Excessively high stresses have a detrimental effect directly on the interface when the stress differences between two layers are too great. On the other hand, if there is a stress, the energy thereby stored in the layer and between the layers increases with the thickness of the corresponding layer, so that cracks may be formed when a particular layer thickness is exceeded. The first case is attributable to the second case.
Another problem is that, because of particles which enter the layers during the production method, a minimum thickness of the thin-film structures should be achieved in order to achieve a particular storage stability, although because of the stresses in the layers this may in turn lead to formation of cracks and therefore reduction of the storage stability.
In order to solve the aforementioned problems, for example, stress-compensated layer sequences may be formed by CVD methods in order to increase the robustness of the encapsulation layer structure (TFE). Such encapsulations are known inter alia in SiNC layer sequence systems, although these only achieve a minimum water permeability of 10−4 g/m2/d and therefore do not generally satisfy the OLED requirements. The required mechanical stability of the cathode and/or thin-film layers may be achieved by an encapsulation layer structure including the layer sequence SiN/AlOx/TiOx. In this case, however, detachment of the cathode by stressing of the cathode and/or of the encapsulation layer structure is possible. The required leaktightness can be achieved in this way, but the robustness in respect of particles is only mediocre. Another possibility is the formation of a thick CVD layer. This leads to a high storage stability. Without stress compensation, however, the risk of layer detachment increases. Although the hermetic leaktightness and the robustness against particles increases with the thickness of the CVD layers, the economic viability of thick CVD layers in the μm range is, however, relatively low because of the relatively long process time.